Study On Lithium Performance And Corrosion Resistance Of TiO 2

TiO₂ is widely used as a kind of semiconductor material which is widely studied because of its low cost, easy to obtain and environment friendly. TiO₂ as lithium ion battery cathode material with good electrochemical activity, because of its high charging and discharging （1.7V）, not only to avoid the formed in the low voltage of lithium dendrite caused by security issues, but also not produce on the surface of the electrode formation solid electrolyte interface film （SEI film）, and abundant in nature,so TiO₂ is found to be an ideal substitute for substitution of carbon anode material. But in actual use, TiO₂ discharge capacity can only reach 50% of the theory. At present mainly through the preparation of various morphologies of TiO₂ nanometer materials to improve capacity, TiO₂ nanotube with its large specific surface area, which can fully contact with the electrolyte, and also can effectively shorten the lithium ion diffusion distance,which with these advantages has become a hot research topic in the lithium ion battery cathode material, but it is still difficult to make length for micron sized TiO₂ nanotubes, which limit the TiO₂ nanotube widely used in the field of lithium batteries and photocatalysis.This dissertation proposes adding mechanical force field during preparation of TiO₂ nanotubes in the hydrothermal process, due to mechanical force field in the hydrothermal reaction in the process of stirring improve the diffusion velocity and surface chemical reaction velocity of ions in solution, so as to improve the rate of formation of the nanotubes in solution, the nanotubes can grow very long in a short time so that we can successfully prepare super-long TiO₂ nanotubes.As the TiO₂ nanotubes prepared by hydrothermal method at different annealing temperature have different crystal structures at the same time TiO₂ nanotubes with different crystal structures with different intercalation mechanism. This paper we prepare different temperature （400/500/600） of fine long TiO₂ nanotube electrode materials for annealing. Characterization of very fine and long TiO₂ nanotubes as electrode materials for lithium ion batteries assembled with half cell electrochemical performance test.We found very fine long TiO₂ nanotubes lithium battery compared with ordinary hydrothermal preparation of TiO₂ nanotube lithium battery performance had greatly improved. Take 500 degree annealing anatase phase for example, previous studies have shown that, the anatase phase of TiO₂nanotubes first discharge capacity of about 170 MAH g-1, this experiment measured and it is still in 205 Mah/g very fine, ultra long TiO₂ nanotubes anatase phase of the discharge capacity reached 250 mAhg-1 after 100 circulation, circulation ratio test capacity remained stable and no leaping reduced, after the impact of high current density reversible capacity is still to maintain 90% of the initial capacity. At the same time lithium TiO₂ nanotubes are other crystal forms of fine long has greatly improved.Although the very fine long TiO₂ nanotubes show excellent block the electrochemical properties of lithium and good structure stability, but due to the theoretical capacity limited, which can not meet requirements of consumer electronics and electric vehicles for high capacity high energy density lithium-ion battery, which doped with high theoretical capacity of a material to enhance capacity. Silicon is a material with high theoretical capacity, theoretical capacity up to 4200mah/g, which has good prospects for the study, but silicon material in lithium ion intercalation and deintercalation process will generate bulk volume changes, circulation process easy to be broken and detached from the electrode material, which results in capacity decay rapidly. Proposed in this paper of silicon nanoparticles coated carbon layer is formed silicon carbon composite structure, doping in TiO₂ nanotubes with very fine long, constitute a three-dimensional network structure of TiO₂/Si/C composite, composed of very fine ultra long TiO₂ nanotubes three-dimensional network structure can limit the volume change of silicon carbon composite structure of the charge and discharge process of, and TiO₂ in itself also has capacity contribution, so as to improve the performance of the lithium battery, after 25 cycles capacity remains at 430 mAh/g. TiO₂/Si/C composite material has a certain excellent structure, but in the process of multiplying power cycle, due to the rapid change of current will cause a certain structural dmAage, the follow-up will continue to study.With the process of Titanium shot peening surface nano, plasma permeability or ion was implanted with Ni,then anodic was oxidized, preparation doped with TiO₂ nanotube arrays with embedded lithium metal oxide process. It is found that the titanium surface by Double Glow Plasma Permeability specimens of nickel is difficult to oxidation, electrochemical corrosion properties found anti -corrosion performance has been improved, so this phenomenon is explored.